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mirror of git://sourceware.org/git/glibc.git synced 2024-12-09 04:11:27 +08:00
glibc/nss/nss_files_data.c
Florian Weimer 36861a968a nss_files: Add generic code for set*ent, end*ent and file open
This reduces RSS usage if nss_files is not actually used, and can
be used later to make NSS data thread-specific.  It also results in
a small code size reduction.

Before:

   text	   data	    bss	    dec	    hex	filename
   2288	      0	     72	   2360	    938	nss/files-alias.os
   1807	      0	     72	   1879	    757	nss/files-ethers.os
   1371	      0	     72	   1443	    5a3	nss/files-grp.os
   6246	      0	     72	   6318	   18ae	nss/files-hosts.os
    869	      0	      0	    869	    365	nss/files-initgroups.os
    666	      0	      0	    666	    29a	nss/files-init.os
   1934	      0	      0	   1934	    78e	nss/files-netgrp.os
   2353	      0	     72	   2425	    979	nss/files-network.os
   2130	      0	     72	   2202	    89a	nss/files-proto.os
   1372	      0	     72	   1444	    5a4	nss/files-pwd.os
   2124	      0	     72	   2196	    894	nss/files-rpc.os
   2265	      0	     72	   2337	    921	nss/files-service.os
   1125	      0	     72	   1197	    4ad	nss/files-sgrp.os
   1124	      0	     72	   1196	    4ac	nss/files-spwd.os

After:

   text	   data	    bss	    dec	    hex	filename
   2040	      0	      0	   2040	    7f8	nss/files-alias.os
   1599	      0	      0	   1599	    63f	nss/files-ethers.os
   1155	      0	      0	   1155	    483	nss/files-grp.os
   6010	      0	      0	   6010	   177a	nss/files-hosts.os
    869	      0	      0	    869	    365	nss/files-initgroups.os
    666	      0	      0	    666	    29a	nss/files-init.os
   1934	      0	      0	   1934	    78e	nss/files-netgrp.os
   2129	      0	      0	   2129	    851	nss/files-network.os
   1914	      0	      0	   1914	    77a	nss/files-proto.os
   1156	      0	      0	   1156	    484	nss/files-pwd.os
   1908	      0	      0	   1908	    774	nss/files-rpc.os
   2057	      0	      0	   2057	    809	nss/files-service.os
    909	      0	      0	    909	    38d	nss/files-sgrp.os
    908	      0	      0	    908	    38c	nss/files-spwd.os
   1090	      0	      8	   1098	    44a	nss/nss_files_data.os

27674 code bytes before, 26344 code bytes after, so it is an overall
win despite the extra initialization code.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2021-07-07 18:33:52 +02:00

162 lines
4.5 KiB
C

/* Returns a pointer to the global nss_files data structure.
Copyright (C) 2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <nss_files.h>
#include <allocate_once.h>
#include <errno.h>
#include <netdb.h>
#include <nss.h>
#include <stdlib.h>
/* This collects all per file-data. */
struct nss_files_data
{
struct nss_files_per_file_data files[nss_file_count];
};
/* For use with allocate_once. */
static void *nss_files_global;
static void *
nss_files_global_allocate (void *closure)
{
struct nss_files_data *result = malloc (sizeof (*result));
if (result != NULL)
{
for (int i = 0; i < nss_file_count; ++i)
{
result->files[i].stream = NULL;
__libc_lock_init (result->files[i].lock);
}
}
return result;
}
/* Like __nss_files_data_open, but does not perform the open call. */
static enum nss_status
__nss_files_data_get (struct nss_files_per_file_data **pdata,
enum nss_files_file file, int *errnop, int *herrnop)
{
struct nss_files_data *data = allocate_once (&nss_files_global,
nss_files_global_allocate,
NULL, NULL);
if (data == NULL)
{
if (errnop != NULL)
*errnop = errno;
if (herrnop != NULL)
{
__set_h_errno (NETDB_INTERNAL);
*herrnop = NETDB_INTERNAL;
}
return NSS_STATUS_TRYAGAIN;
}
*pdata = &data->files[file];
__libc_lock_lock ((*pdata)->lock);
return NSS_STATUS_SUCCESS;
}
/* Helper function for opening the backing file at PATH. */
static enum nss_status
__nss_files_data_internal_open (struct nss_files_per_file_data *data,
const char *path)
{
enum nss_status status = NSS_STATUS_SUCCESS;
if (data->stream == NULL)
{
data->stream = __nss_files_fopen (path);
if (data->stream == NULL)
status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
}
return status;
}
enum nss_status
__nss_files_data_open (struct nss_files_per_file_data **pdata,
enum nss_files_file file, const char *path,
int *errnop, int *herrnop)
{
enum nss_status status = __nss_files_data_get (pdata, file, errnop, herrnop);
if (status != NSS_STATUS_SUCCESS)
return status;
/* Be prepared that the set*ent function was not called before. */
if ((*pdata)->stream == NULL)
{
int saved_errno = errno;
status = __nss_files_data_internal_open (*pdata, path);
__set_errno (saved_errno);
if (status != NSS_STATUS_SUCCESS)
__nss_files_data_put (*pdata);
}
return status;
}
libc_hidden_def (__nss_files_data_open)
void
__nss_files_data_put (struct nss_files_per_file_data *data)
{
__libc_lock_unlock (data->lock);
}
libc_hidden_def (__nss_files_data_put)
enum nss_status
__nss_files_data_setent (enum nss_files_file file, const char *path)
{
struct nss_files_per_file_data *data;
enum nss_status status = __nss_files_data_get (&data, file, NULL, NULL);
if (status != NSS_STATUS_SUCCESS)
return status;
if (data->stream == NULL)
status = __nss_files_data_internal_open (data, path);
else
rewind (data->stream);
__nss_files_data_put (data);
return status;
}
libc_hidden_def (__nss_files_data_setent)
enum nss_status
__nss_files_data_endent (enum nss_files_file file)
{
/* No cleanup is necessary if not initialized. */
struct nss_files_data *data = atomic_load_acquire (&nss_files_global);
if (data == NULL)
return NSS_STATUS_SUCCESS;
struct nss_files_per_file_data *fdata = &data->files[file];
__libc_lock_lock (fdata->lock);
if (fdata->stream != NULL)
{
fclose (fdata->stream);
fdata->stream = NULL;
}
__libc_lock_unlock (fdata->lock);
return NSS_STATUS_SUCCESS;
}
libc_hidden_def (__nss_files_data_endent)